Embodiments of the present disclosure relate to a radio base station, a mobile station and a method for determining a transmitting power. More specifically, the present disclosure relates to a radio base station for determining a transmitting power of a mobile station, a mobile station and a corresponding method.
In a Multiple-Input Multiple-Output (MIMO) communication system, Equal Power Allocation (EPA) is usually adopted to make a plurality of mobile stations in different spatial beams transmit signals at a same transmitting power. For example, in a system implemented by using a Non-Orthogonal Multiple-Access (NOMA) technology and a Multi-User Multiple-Input Multiple-Output (MU-MIMO) technology, a plurality of mobile stations connected with a same radio base station can form mobile station pairs, and mobile stations in each mobile station pair share same time and frequency resources. According to the NOMA technology, a communication system may include two functional levels. When the mobile stations in the mobile station pair are located at different functional levels, data transmissions of two mobile stations in the mobile station pair may be distinguished by transmitting powers. In another aspect, when the mobile stations in the mobile station pair are located at a same functional level, the two mobile stations may be located in different spatial beams according to the MIMO technology; in this case, signal transmissions of the two mobile stations in the mobile station pair are distinguished by the different spatial beams, and transmitting powers are allocated equally to the two mobile stations. However, since channel states of the mobile stations are different, the same transmitting power may cause deterioration to communication states of the mobile stations.
In order to improve allocation of the transmitting power, it has been proposed that an optimum transmitting power allocated to each mobile station is determined in a manner of exhaustive search, so that a throughput is maximized when the mobile station transmits signals at the optimum transmitting power. However, a calculation that the optimum transmitting power allocated to each mobile station is determined in a manner of exhaustive search is relatively complex, and a signaling overhead required to transmit the searched optimum transmitting power to the mobile station is high.